Devarim (8:17) and you say to yourselves, “My own power and the might of my own hand have won this wealth for me.”
Devarim (8:18) Remember that it is your God who gives you the power to get wealth, in fulfillment of the covenant made on oath with your fathers, as is still the case.
Chovas HaLevavos (3:64): One should not think that his livelihood depends on a particular means and that if these means fail, his livelihood will not come from a different means. Rather, trust in the Al-mighty, and know that all means are equal for Him. He can provide using whatever means and at any time and however He so wishes, as written "for with the L-ord there is no limitation to save with many or with few" (Shmuel I 14:6), and "But you must remember the L-ord your G-d, for it is He that gives you strength to make wealth, in order to establish His covenant which He swore to your forefathers, as it is this day." (Devarim 8:18), and "Not by might nor by power, but by My spirit, says the L-ord of Hosts." (Zecharia 4:6).
Ramchal (Daas Tevunos 36:05)The third belief, is the belief of many people, that think that the matters of this world follow rules of nature that were established by the creator in the lower worlds, and it is their efforts and pressure that helps and their laziness that does harm as in (Deuteronomy 8:17) "My strength and vigor of my hand achieved this success" and they say further, all is dependent on luck, and it is happenstance for everyone equally, and there is nothing other than the natural way, no more, whether for the good or for the bad:
Ibn Ezra (Devarim 8:17) BUT THOU SHALT REMEMBER. This means if the thought My power and the might of my hand hath gotten me this wealth should enter your mind, then remember the One who gives you power.
Or HaChaim (Devarim 8:17) "You shall remember the Lord your G'd, etc." Moses means that we must remember that the source of all the good we will experience is G'd and we must never forget it. If He had not imbued us with strength we could never have achieved what we imagine we have achieved with our own power. Whenever people turn away from religion, if ever so slightly, it is because they forget that their achievements are not truly their own. Such a path leads to a person's eventual destruction. This may be the reason this verse is immediately followed in the next paragraph by the dire warnings about what will happen when Israel "forgets" its G'd deliberately. Once you forget that G'd is the source of all the good you experience, you will eventually forget that you have a very exclusive G'd altogether. Once that happens, you will seek out other deities. Not only will you contemplate idol worship but you will engage in it actively. Not only will this be some kind of loosely defined service, but you will even prostrate yourself in front of such images. Sanhedrin 60 teaches that if one prostrates oneself in front of the idol Markolies one is guilty of idolatry even though this is not an accepted form of worship for that idol.
Rabbeinu Bachya Devarim (8:17) “and you will say in your heart: “My strength and the power of My hand, etc.” Moses says that possibly your arrogance will become such that you ascribe your affluence to your horoscope. ‘My strength’ would refer to influences from outer space, astrological in nature, the ‘power of My hand י would refer to sub-terrestrial influences, demons resident below earth.
